The present invention relates to an ink-jet recording head for ejecting ink droplets by displacing a piezoelectric element, in which a vibration plate constitutes a part of a pressure generating chamber communicating with a nozzle orifice that ejects ink droplets, and the piezoelectric element is provided via the vibration plate. Moreover, the present invention relates to an ink-jet recording apparatus.
As an ink-jet recording head for ejecting ink droplets from a nozzle orifice, in which a vibration plate constitutes a part of a pressure generating chamber communicating with a nozzle orifice that ejects ink droplets, and the vibration plate is deformed by the piezoelectric element to pressurize ink in the pressure generating chamber, the following two types have been put into practical use. One uses a piezoelectric actuator of a longitudinal vibration mode, which stretches and contracts in an axial direction of the piezoelectric element; the other uses a piezoelectric actuator of a flexural vibration mode.
The former ink-jet recording head can change the volume of the pressure generating chamber by allowing an end face of the piezoelectric element to abut against the vibration plate, thus making it possible to manufacture a head suitable for high density printing. On the contrary, a difficult process, in which the piezoelectric element is cut and divided into a comb teeth shape to make it coincide with an array pitch of the nozzle orifice, and an operation of positioning and fixing the cut and divided piezoelectric element onto the pressure generating chamber are required for the former ink-jet recording head, thus there is a problem of a complicated manufacturing process.
Meanwhile, the latter ink-jet recording head has had an advantage that the piezoelectric element can be fixedly installed into the vibration plate in relatively simple steps of adhering a green sheet of a piezoelectric material to the vibration plate so as to fit the green sheet to a shape of the pressure generating chamber and of sintering the same. However, the latter ink-jet recording head has been involved in a problem of difficulty in a high density array of the pressure generating chambers, which originates from a need of a certain amount of area because of utilization of the flexural vibration.
In order to solve a disadvantage of the latter ink-jet recording head, as disclosed in Japanese Patent Laid-Open No. Hei 5(1993)-286131, an ink-jet recording head has been proposed, in which a piezoelectric material layer having an even thickness is formed over the entire surface of a vibration plate by a film growth technology, and this piezoelectric material layer is cut and divided by a lithography method so that each piece of the layer can correspond to a shape of each pressure generating chamber, thus forming each piezoelectric element so as to be independent for each pressure generating chamber.
However, the above-described ink-jet recording head has been involved in a problem that cracks and the like occur in the vibration plate due to repeated deformations by driving the piezoelectric element. Particularly, a region of the vibration plate near an end portion of the pressure generating chamber in its longitudinal direction is apt to cause damage such as cracking because of a large amount of deformation due to the drive of the piezoelectric element.